I purchased a new MediaTek GPS from the store and am curious about the specifications on it. The GPS unit itself can run at up to 5.0V but there is no documentation showing that the adapter board can run at 5.0V. Looking around on other threads, I'm wondering if it's limited to 3.3V as that seems to be what I have read. What further confuses me though is that the bottom of the board where it has the solder pads shows VCC to be 5V. What are the specs for this unit?
Another question is that I see on the store that there is example code to read data from this GPS for a standard Arduino. I would like to test it out just to make sure I don't have a problem with the GPS. Assuming the adapter board can take 5V (that's why I ask above), I only need to upload the example code to the Arduino, then connect VCC and GND of the GPS to the board and then OUT from the GPS to Serial in 0 correct? I will be using an Arduino Pro to test it out.
One last question, when updating the firmware on the GPS, I know you need an FTDI cable of some sort and I have one but it's a 5.0V version that I have so if the adapter board doesn't take 5.0V, how am I supposed to update it?
Thanks. I'm excited to be able to connect the GPS up to the ArduPilot tomorrow once I can open it and go from there. Until then, I'll be testing the GPS out to see if I can get any data from it.
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The MT3229 module is spec'd up to 5v max, but the nominal supply is 3.3v. While it might be possible to connect the 3229 to 5v power, it is absolutely not recommended because if your power supply runs hot you may be making 3229 flavor toast.
They DIY store's adapter board will make life easy for you. It has a regulator to drop the voltage to 3.3v. Thus you may safely power the module through the adapter at 5v. Yes, 5v is the designed Vcc input to the adapter.
Those 2v and 3v parts are great for power saving in commercial products, but live a short life in the hands of hobby users, 75% of whom have 5v only benches. Like with the compass module, Jordi has not just made it easier to solder the GPS, but he has taken care of getting the voltages safe for 5v use.
The 5V FTDI cable will be fine. For those who still need to buy a cable, I'd get the 3.3v one since more parts in the future will likely be 3v than 5v. I have 1 of each, and took a wrap of green electrical tape around each end of the 3v cable and a wrap of red electrical tape at each end of the 5v cable. This makes for fast visual identification. Green safe. Red danger.
Be aware that the "standard" 3v FTDI cable (available here, SparkFun, etc.) has 3v data lines, but (because of a mistake in the original design which has been retained for compatibility) the power output is actually 5v. If you go direct to FTDI you can get the cable in all sorts of variations including 3v power.
Correct--you only need the 4 wires you mentioned to make an Arduino communicate with the GPS. In fact, if you don't mind listening only, (default baud rate, message rate, NMEA, etc.) you can use just 3 wires. The Arduino-out/GPS-in wire is optional if you are desperately short of serial lines.
If you are new to programming and such, and aren't sure if you've gotten the Arduino listening and parsing the buffer, you can test your GPS without the Arduino. Just use the FTDI cable to connect the GPS to a computer like you were going to update the firmware. Then open any terminal emulator (Mac, Windows, Linux) (using the proper comm ports, baud rate, etc. of course) and watch the NMEA scroll by. Log it to a file for later analysis. Or use the configuration utility software (Windows only) that comes in the same zip file with the firmware update software. It will give you position, time, sats, health, in a human friendly form.